Medical ultrasound hardware utilizes a mechanical transducer to broadcast high-frequency acoustic waves through the human body and then measure the reflection as a means for imaging. To use ultrasound imaging in the clinical setting, ultrasound operators must follow a strict convention to ensure that the image is oriented appropriately and the underlying anatomy is diagnosed correctly. By convention, the transducer is marked with a protruding indicator that must be oriented towards a patient's head or anatomic-right side during scanning. To aid guidance, a matching probe indicator icon is displayed on the screen of the ultrasound machine as a reference (generally on the left side of the screen). Maintaining this strict orientation takes on added significance when performing image-guided interventions (e.g., needle insertion), which may result in catastrophic implications if not performed correctly. For instance, a common pitfall, especially for novice users, is to inadvertently reverse the indicator default setting and erroneously orient the transducer as they are performing an incorrectly oriented, image-guided medical intervention.
However, by embedding motion-sensing technology directly within the housing of the ultrasound transducer (ultrasound probe), the position and orientation of the device can be tracked in relation to an indicator mark on the ultrasound screen in an automated manner, allowing assisting technologies to mitigate human error that arises from misalignment of the transducer indicator. As an example, motion sensors can be used to detect misalignment and provide visual or auditory alerts to notify the user about the probe indicator alignment (e.g., a probe indicator icon moves along the ultrasound screen in relation to the actual probe's orientation relative to a patient's body-rather than a preset position).
Furthermore, motion sensing hardware is employed by commercial solutions that provide real-time or just-in-time refresher training of ultrasound skills in a simulated environment. These simulators employ a motion-controlled handheld device in the shape of an ultrasound probe to recreate the experience of using a real device on a wide selection of pre-recorded patient cases with or without serious clinical pathologies. However, these simulators are currently only available as dedicated workstations or software packages for personal computers (PCs) and require an ad hoc external handheld motion sensing peripheral device for control. As a result, it is not possible to currently integrate the benefits of ultrasound training simulators within a real ultrasound device. The addition of an embedded motion sensor directly inside an ultrasound transducer will make this possible.
Having motion-sensing technology embedded directly within the housing of an ultrasound transducer will enable ultrasound devices to operate in two separate modes: a standard mode that allows the user to scan real patients using the traditional physics of ultrasound as is done currently, and a training mode that will instead allow the user to employ the same ultrasound probe as a motion sensing peripheral to navigate a multitude of existing patient cases augmented with annotations that help the operator expand and refine his or her knowledge of ultrasound imaging.
A typical handheld motion sensor utilizes various sensing components to measure displacement and orientation in three-dimensional (3D) space, for example, with a six degree of freedom (6-DOF) sensor. While many technologies exist for tracking motion in space, inertial solutions allow the sensor package to retain a small form factor and work without needing additional external components to act as a fixed point of reference. Most inertial solutions combine accelerometers, gyroscopes, and a magnetometer in a single package to measure inertial motion and relate the orientation of the device with respect to the gravity vector and the earth's magnetic field. Whereas it has been previously proposed that this technology reside in a plastic casing of its own, it is now proposed that the electronic hardware be embedded and integrated within the plastic housing of current medical ultrasound transducers.
Also, to improve the fidelity of the simulation in training mode, an additional sensor (a “6+1 DOF” sensor) may be added to the embedded package for measuring compression, allowing the user to investigate the elastic properties of the underlying anatomy in the simulated environment by pressing the tip of the device against a surface with varying amounts of force.